Nasdaq turns positive on biotech boost

The Nasdaq turned positive on Monday as shares of biotechnology companies advanced, but the drag from retreating commodity prices kept both the Dow and the S&P 500 in negative territory.

* The rise in biotechnology companies followed a brokerage's raised recommendation on Celgene Corp , up almost 5 percent at $55.02.

* A weaker-than-expected reading in a forward-looking measure of the U.S. economy also curbed the broader market.

* The Dow Jones industrial average was down 35.22 points, or 0.36 percent, at 9,784.98. The Standard & Poor's 500 Index was down 3.72 points, or 0.35 percent, at 1,064.58. The Nasdaq Composite Index was up 4.12 points, or 0.19 percent, at 2,137.00.